Current pharmacologic strategies fail to achieve effective reperfusion in 30 percent or more of acute myocardial infarction (MI) patients, and many patients with occluded infarct-related arteries (IRAs) do not meet current criteria for use of these agents. Early angioplasty, an effective reperfusion method, is available to a small proportion of potentially eligible acute MI patients in the U. S. Hence, a substantial number of acute MI patients pass the time when reperfusion therapy has well documented benefit (12-24 hours) with a persistently closed IRAs. Several lines of experimental and clinical evidence suggest that late reperfusion of these patients could provide clinically significant reductions in mortality and morbidity. Hypothesis. Opening an occluded IRA 3-21 days after an acute MI in high-risk asymptomatic patients (ejection fraction less than 50 percent or proximal occlusion of a large coronary artery) will reduce the composite end point of mortality, recurrent MI, and hospitalization for NYHA Class IV congestive heart failure (CHF) over an average 3-year follow-up. Study aims. In the Open Artery Trial (OAT) 3,200 patients will be randomly allocated in equal proportions to the two treatments over two years. One treatment will consist of conventional medical management (including aspirin, beta blockers, ACE inhibitors, and risk factor modification). The experimental treatment will consist of conventional medical therapy plus percutaneous coronary intervention and coronary stenting. The primary specific aim is to compare the composite outcome of all-cause mortality, non-fatal MI and hospitalization for Class IV CHF based on an average 3-year follow-up among patients assigned to the two treatments. Three secondary specific aims are to compare: 1) the individual components of the study composite primary end point in the two treatments; 2) the medical costs of the two treatments; and 3) health-related quality of life in the two treatments. Role of Data Coordinating Center. This application is made for support of a Data Coordinating Center (DCC) at the Maryland Medical Research Institute. The DCC is responsible for statistical design and power calculations, random treatment assignments, data management, support for the Mortality and Morbidity Classification Committee, rapid communication and generation of performance data for review with the Study Chair and Co-Chair of the Clinical Coordinating Center and data analysis to assess treatment effects.